Push-pull circuit for amplifying or producing high-frequency oscillations



Sept. 18, 1956 MULDER 2,763,734

H. H. PUSH-PULL CIRCUIT FOR AMPLIFYING OR PRODUCING HIGH-FREQUENCY OSCILLATIONS Filed Aug. 16, 1952 INVENTOR HARM HENDRIK MULDER AGENT PUSH-PULL UIRC'UIT FOR AMPLIFYING R PRO- lD UClNG HIGH-FREQUENCY OSCILLATIONS Harm Hendrik Mulder, Eindhoven, Netherlands, assignor to Hartford National Bank and Trust Company, Hartford, Conn, as trustee Application August 16, 1952, Serial No. 304,823

Claims priority, application Netherlands September 21, 1951 2 Claims (Cl. 179-171) This invention relates to push-pull circuits comprising tuned input and output circuits for amplifying or generating high-frequency oscillations.

As is well-known, in push-pull oscillators or push-pull amplifiers, comprising grid'controlled electron discharge tubes of a given type it is possible, without utilizing tubes suitable for a higher output, to increase the output by the use of a plurality of tubes in parallel combination per push-pull branch. However, the output and hence the efiiciency which may in practice be obtained with such circuits, more particularly at frequencies higher than 100 megacycles per second, does not come up to expectatrons.

The object of the invention is to provide a push-pull circuit comprising a plurality of parallel-operating, gridcontrolled electron discharge tubes per push-pull branch, which makes it possible to obtain a reasonable output even at ultra-high frequencies of, for example, 200 to 300 megacycles per second.

According to the invention, each pair of amplifying tubes connected in push-pull is coupled to a separate, tunable grid circuit, whereas for each push-pull branch the anodes of the parallel-operating tubes are jointly coupled to a tuned anode circuit which is common to all tubes.

When directly connecting in parallel a plurality of tubes in conventional circuits of this type, the tube impedances and/or grid-circuit impedances, which in this case are connected in parallel, are in practice objectionable. This is particularly so at ultra-high frequencies, whereas the parallel-operating tubes provided in the circuit according to the present invention have separate grid circuits, to avoid objections of this kind.

In order that the invention may be clearly understood and readily carried into effect, it will now be described in detail with reference to the accompanying drawing, wherein the figure is a schematic diagram of a preferred embodiment of a push'pull oscillator circuit according to the present invention. This embodiment comprises two parallel-operatingpush-pull systems.

in the figure, one push-pull system comprises screengrid electron discharge tubes 1 and 2, the control grids of which are connected in push-pull to a first tunable grid circuit 3. The control grids of the other push-pull system comprising screen-grid electron discharge tubes 4 and 5 are connected in push-pull to a second tunable grid circuit 6. Center taps of the distinct grid-circuits 3 and d are connected to ground by way of grid-current limiter resistances '7, 8 and grid-current meters 9, 10 respectively. The grid circuits of the push-pull systems are thus fully separate.

The anode circuit which is common to the push-pull systems is constituted by a Lecher circuit 11, which may nited States Patent 0 ice be tuned to a frequency in the ultra-high frequency range, comprising a load circuit 12, a tuning bridge 13 and a supply conductor 14-. The supply conductor 14 is connected by way of an ammeter 15 to an anode-voltage source 16. The anodes of the tubes 1 and 4 are connected in parallel to one extremity of the Lecher circuit 11, the anodes of the tubes 2 and 5 being connected in parallel to the other extremity of the Lecher circuit 11.

The circuit shown substantially comprises two pushpull oscillators having the tubes 1, 2 and 4, 5 respectively, which comprises separate grid-circuits and a common anode circuit, the common anode circuit bringing about synchronization of the push-pull oscillators. The excitation phase of the push-pull oscillators which is optimum for maximum output is adjustable by adjusting the resonant frequency of the grid circuits 3 and 6.

The oscillator circuit shown may be extended at will by other push-pull oscillators each having a grid circuit associated with it.

instead of utilizing for each push-pull oscillator, tube systems housed in separate envelopes, use may be made of, for example, double tetrodes of the type Philips QQE 06/40 or similar tubes.

It is to be understood that the invention is not limited to the details disclosed but includes all such variations and modifications as fall within the spirit of the invention and the scope of the appended claims.

What I claim is:

l, A high-frequency push-pull parallel circuit arrangement comprising a pair of push-pull signal branches each comprising first and second electron discharge tubes each having a cathode, an anode, a control electrode and a screen electrode, common coupling means: connecting the cathodes of said first and second tubes, common coupling means connecting the screen electrodes of said first and second tubes, first and second resonant push-pull input circuits each being connected between the control electrodes of the first and second tubes of a respective one of said branches, means for connecting the midpoint of each of said input circuits to the common cathode coupling of said first and second tubes of its respective branch, common coupling means connecting the anodes of the first tubes of said branches, common coupling means connecting the anodes of the second tubes of said branches, at tuned transmission line tuned to a frequency in the ultra-high frequency range having first and second con doctors, one end of said first conductor being connected to the first-mentioned common anode coupling and one end of said second conductor being connected to the second-mentioned common anode coupling, common coupling means connecting the other ends of said first and second conductors, and means for applying a positive potential relative to said cathodes to the electrical midpoint of said last-mentioned common coupling means, said input circuits being adjustable thereby to vary the signal excitation of said branches.

2. A push-pull parallel oscillator comprising a pair of push-pull signal branches, each branch including first and second electron discharge tubes provided with a cathode, a grid and an anode, first and second resonant push-pull input circuits each having opposite ends thereof connected to the grid of a respective one of said tubes, means connecting the midpoint of each of said input circuits to the cathode of the tubes of the respective branches, a tuned transmission line tuned to a frequency in the ultra'high frequency range having first and second conductors, one end of said first conductor being connected to the anodes 3 of the first tubes in said branches and one end of said second conductor being connected to the anodes of the second tubes in said branches, and means to apply a positive potential relative to cathode to the other ends of said conductors, said input circuits being adjustable thereby to vary the signal excitation of the respective branches.

References Cited in the file of this patent UNITED STATES PATENTS 1,666,158 Affel Apr. 17, 1928 4 Marshall May 1, Weston Apr. 9, Curtis Mar. 21, Parker Sept. 5, Kinn Nov. 11, Long Jan. 16, 

